The sequence of maturation of sensory receptors will be mapped in the larynx of embryonic and juvenile rhesus monkeys. The developmental sequence of mechanoreceptors as well as chemoreceptors will be traced using light and electron microscopy emphasizing the possible role of sensorineural laryngeal mechanisms in the etiology and/or pathogenesis of the Sudden Infant Death Syndrome (SIDS). The sensorineural maturation of mucosal sensory receptors will be compared with the maturation of receptors in ligaments and joints in the laryngeal complex. The sensorineural maturation of the laryngeal complex will be compared with the maturational sequence of other areas of pharynx and oral cavity known to be sites of importance in the initiation of reflexes modulating respiratory activity. The baseline data from the rhesus monkey will be used to assist in the evaluation of the sensorineural status of limited suitable human autopsy tissue.